RADIATION SAFETY - PowerPoint PPT Presentation

Loading...

PPT – RADIATION SAFETY PowerPoint presentation | free to view - id: 816b34-ZDA0N



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

RADIATION SAFETY

Description:

RADIATION SAFETY Junior Radiology ... mutagenic or even lethal Patients undergoing these types of studies are exposed to Ionizing Radiation: Radiographs Fluoroscopy ... – PowerPoint PPT presentation

Number of Views:337
Avg rating:3.0/5.0
Slides: 28
Provided by: Carol688
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: RADIATION SAFETY


1
RADIATION SAFETY
  • Junior Radiology Course

2
Expectations for the Junior Radiology Course
  • Medical School wants students to learn basic
    principles, factual knowledge, safety info, etc.
  • Medical Students want to learn how to read films!

3
What is an X-ray?
  • a form of radiant energy similar in several
    respects to visible light
  • As is the case for rays of light, a small part of
    an X-ray beam will be absorbed by air, and all of
    the beam will be absorbed by a thick metal
    barrier
  • Main difference
  • X-rays have much shorter wavelengths than those
    of UV light

4
What is an X-ray?
  • X-rays are very short wavelength electromagnetic
    radiation
  • The shorter the wavelength, the greater the
    energy and the greater the ability to penetrate
    matter
  • X-rays are described as packets of energy called
    Quanta or Photons
  • Photons travel at the speed of light
  • Photon energy is measured in electron volts

5
Ionization
  • An atom which loses an electron is ionized
  • Photons having ? 15 electron volts can produce
    ionization in atoms and molecules
  • X-Rays, Gamma Rays, and certain types of UV
    Radiation are Ionizing Radiation

6
Ionizing Radiation in Radiology
  • Ionizing Radiation can be carcinogenic and, to
    the fetus, mutagenic or even lethal
  • Patients undergoing these types of studies are
    exposed to Ionizing Radiation
  • Radiographs
  • Fluoroscopy/Conventional Angiography
  • CT
  • Nuclear Medicine

7
Goals of Radiation Safety
  • Eliminate deterministic effects
  • Reduce incidence of stochastic effects

8
Exposure to Ionizing Radiationcauses two types
of effects
  • Deterministic Effects A minimum threshold dose
    must be attained for the effect to occur.
    Examples include cataract formation, skin
    reddening (erythema), and sterility. Also
    referred to as non-stochastic effects
  • Stochastic Effects The effect may (potentially)
    occur following any amount of exposure there is
    no threshold. Examples include cancer and
    genetic defects.

9
RadTech uses collimation and lead apron to reduce
unwanted exposure
10
RADIOGRAPHY
  • X-ray photons are produced when a Tungsten anode
    is bombarded by a beam of electrons
  • Matter absorbs or scatters the X-rays
  • Some X-rays reach the cassette, which contains an
    image receptor (either a sheet of film or an
    electronic device)

11
Collimation reduces scatter X-rays, thus
reducing dose to healthcare workers, and also
improving image quality
12
LIMITING YOUR EXPOSURE
  • Three basic methods for reducing exposure of
    workers to X-rays
  • Minimize exposure time
  • Maximize distance from the X-ray tube
  • Use shielding.

13
LIMITING YOUR EXPOSURE You do the math!
  • Doubling your distance from the X-ray tube
    reduces your exposure by a factor of four
  • Tripling your distance from the X-ray tube
    reduces your exposure by a factor of nine!

14
LIMITING YOUR EXPOSURE
  • Maximize distance from the X-ray tube
  • Exposure varies inversely with the square of the
    distance from the X-ray tube

15
LIMITING WORKER EXPOSURE
  • www.e-radiography.net/radsafety/reducing_exposure.
    htm

16
Imaging in Pregnancy
  • Reference
  • 1)       Toppenberg, MD, Hill MD, Miller MS,
    Safety of Radiographic Imaging During Pregnancy,
    American Family Physician, Vol. 59, No. 7, pp.
    1813 1818, April 1, 1999.
  • 2)       Roberts MD, Radiographic Imaging During
    Pregnancy Plain X-rays, Emergency Medicine
    News, Vol. 24, No. 3, March 2002.
  • 3)       Roberts MD, Radiographic Imaging During
    Pregnancy MRI and CT Scan, Emergency Medicine
    News, Vol. 24, No. 4, April 2002.

17
Risk to Fetus
  • Radiation causes harm through the excitation
    created by X-ray photons striking atoms, which
    may either disrupt the molecule directly, or
    create a free radical, which is capable of
    reacting with other biologic molecules.

18
FETAL EXPOSURE
  • The maximal limit of ionizing radiation to which
    the fetus should be exposed during pregnancy is a
    cumulative dose of 5 rad.

19
Radiation Exposure
  • Cervical spine 0.002
  • Upper or lower extremity 0.001
  • Chest (two views) 0.00007 gt70,000
    exams to reach max exposure
  • Abdominal (multiple views)0.245

20
Pregnancy Radiation Risk
  • For counseling purposes, know that at doses lt 5
    rem, there have been no proven effects on the
    fetus, but extrapolation from higher doses
    suggests that the risk is 0.5-1/rem for
    radiation induced congenital defects. The natural
    occurrence of congenital defects is approximately
    5.
  • Radiation effects on the fetus are cumulative
    throughout the pregnancy.

21
Basic Radiation and Pregnancy Facts
  • Brian Mullan, M.D.
  • Fetal malformations from radiation are uncommon
    at standard medical doses of radiation, however
    the fetus is most sensitive at 8-17 weeks of
    gestation. Non-urgent studies should be avoided
    in this window.

22
Abdominal Shield
  • If the study is above the abdomen or below the
    hips, no risk is present to the fetus, shield the
    abdomen
  • For studies in which the fetus comes under direct
    exposure of the radiation beam, for all doses of
    radiation 1.Contact staff arrange a
    discussion between the referring physician and
    the staff on-call.

23
STEPS
  • 2.If exam is appropriate and necessary, have the
    clinician write a note in the chart stating the
    study is indicated for the management of the
    patient.
  • 3.Explain the procedure to the patient with the
    assurance that the dose will be kept as low as
    possible consistent with obtaining the diagnostic
    information

24
Risk to Fetus
  • The developing CNS is most frequently affected
    after high levels of radiation in utero, with
    common defects being mental retardation and
    microcephaly. Malignancy can also result, with
    the most common radiation-induced cancer being
    childhood leukemia.

25
Risk for Cancer
  • The probability of developing radiation-induced
    carcinogenesis increases with radiation dose, but
    the severity of the malignancy is independent of
    the radiation dose.
  • Leukemia Most Common

26
Pregnancy
  • MRI There are no documented adverse effects upon
    the fetus, but it is recommended that all
    non-essential studies be avoided in the first
    trimester.
  • Ultrasound Recommended that the average power
    setting for ultrasound studies in the area of the
    fetus be kept to a minimum consistent with
    achieving a diagnostic study.

27
Consent forms
  • 1-5 rem Inform the patient and family of the
    risks and benefits, and have the patient sign the
    informed consent form.
  • gt 5 rem Counsel patient and family about risks
    and benefits. Referring physician, radiologist,
    and radiation physicist should all write notes in
    the patients chart explaining the circumstances
    and medical justification for the exam or
    procedure. Have the patient sign the informed
    consent form.
About PowerShow.com